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Integrated Rainwater Collector and Solar Panel Cooling system

1.0 Background

With the rapidly growing population, the global energy demand is predicted to increase by up to 47% by 2050 compared to 2021 [1]. Despite the rapid growth of renewable energy sources such as wind and solar power, oil remains the largest source of energy worldwide [1]. This is partly due to its high energy density and versatility, but it also reflects the long-standing dominance of the oil industry in many parts of the world. As the population continues to grow, the energy demand will continue to rise, which will put increasing pressure on existing energy systems and infrastructure. However, the continued reliance on fossil fuels such as oil, coal, and natural gas comes with significant environmental costs, including air pollution, greenhouse gas emissions, and the depletion of natural resources [1]. These costs are becoming increasingly apparent as the impacts of climate change become more severe and widespread.

One of the prevalent methods to enhance the power output of a solar panel is to employ a light concentrator system that uses lenses or mirrors to amplify the solar irradiance on a small area of highly efficient solar cells. However, this approach also increases the temperature of the solar panel, which adversely affects its performance and longevity. This issue is often overlooked or neglected when seeking solutions to improve solar panel efficiency [2]. Therefore, our project aims to devise and implement thermal control strategies that can be integrated with the conventional light concentrator system.

2.0 Objective

Our project aims to address the problem of solar power efficiency by integrating a rainwater harvesting system with the solar panel as a cooling mechanism. We recognize the unique challenges faced by the camper communities living off the grid and aim to provide a sustainable solution that meets their energy and water needs. Our system utilizes rainwater collected from various catchment areas, such as rooftops and roads, to cool down the solar panel and increase its power output. By doing so, we can eliminate the loss of energy due to the excessive heat generated by the solar panel, resulting in higher solar power efficiency. In addition, our system also benefits the campervan owners by providing them with access to clean water for their domestic and personal needs. The harvested rainwater can be used for washing utensils, cooking, drinking, and bathing, providing a sustainable alternative to traditional water sources. Our project aims to contribute to the global effort towards sustainable living by reducing energy consumption and water waste. With our innovative solution, we hope to empower campervan owners to live a more self-sufficient and eco-friendly lifestyle, without compromising on their basic needs.

3.0 Literature Review

The research by J.Addeb shows that solar cell performance is influenced by temperature, which decreases the output [3]. The study found that thin-film solar panels are less affected by temperature, making them a better option for specific locations. Abu Syed Keron's research indicates that the output power of a solar cell is significantly affected by the surface temperature. When a cooling system is not used, the surface temperature increases significantly and results in lower overall output compared to when the cooling system is utilized to prevent excessive surface temperature increase. The overall efficiency of the solar PV cells was 1.55% and when cooling was implemented on the panel it increased to 1.66%. from the data [5].

According to Hiroaki's research, porous ceramic materials can achieve a cooling effect through the evaporation of absorbed water [4]. However, the efficiency of this cooling effect through water evaporation from porous ceramic plates is affected by relative humidity and temperature. The data reveals that at a relative humidity of 60% in the inlet air, the temperature difference between the inlet and outlet air (which indicates the cooling effect) is 2.3.

4.0 Methodology

4.1 Effect of Sun Heating on Solar Panel Operation

The experiment was conducted in a controlled environment, by ensuring the solar cell is set up with equal powered lamps surrounding at an equal angle and using a thermal camera for temperature readings as shown in the pictures below. The system includes a solar panel, two support rack structures and a rainwater harvester system that consists of a funnel, a 1.2m long aquarium rubber pipe and a ceramic plate.

Figure 1: Heating solar cell

This experiment was conducted by heating the solar cell from 36.7° to around 93°. The solar cell was heated using the heat from surrounding lamps and a heat gun, at a safe distance, to speed up the heating of the cells. While heating power and efficiency readings were measured. The results taken using the thermal camera are as shown in the figures below.

Figure 4: Low Temperature Simulated In Lab

Figure 2: Thermal Reading under Actual Sun

Figure 3: High Temperature Simulated in Lab

4.2 Integrated Ceramic Cooling System

The experiment was conducted in a controlled environment, by making sure the solar cell was set up using a thermal camera for temperature readings. A ceramic plate was chosen to be used in this project due to its appropriate properties such as high weather resistance, high working temperature and low thermal expansion [3]. Therefore, the ceramic plate was utilised as a platform to absorb the rainwater and release the heat from the solar panel via the evaporation process.

Four equal powered lamps surrounded at an equal angle and this experiment was conducted by measuring the time taken for the solar cell to drop its temperature from 80° down to 45°. The solar cell was heated using the surrounding lamps and a heat gun, at a safe distance, to speed up the heating of the cell. Once heated to 80°, the cell was then left to cool and measurements were recorded during this. This experiment was then repeated by implementing the cooling system using water. The time taken was then compared between the solar cell using the cooling system and the one without.

Figure 5: Measuring Temperature of Ceramic Cooling Plate

Figure 6: Capture of Temperature Data in Lab

5.0 Results and Discussions

5.1 Effect of temperature towards output voltage

In the first experiment, the effect of temperature resulting in the output voltage is obtained by using the method described in the methodology. A graph of output voltage against temperature is also plotted.

Figure 7: Graph of output voltage versus temperature

By observing the data, the output voltage is having inverse relation with temperature. From figure 1, when the temperature is at 36.7 °C, the output voltage obtained is the highest having 20V. On the other hand, as the solar panel is heated until 93.3 °C, the output voltage is 17.1V, the lowest value among all data.

For a short-circuit solar cell, the short-circuited current is increased as the temperature is higher. This is because of higher energy for electron-hole pair to be created. On the other hand, the open-circuit solar cell will provide a low open-circuit voltage as the temperature rose.

The open-circuit voltage is given by

open-circuit voltage equation

As shown in the equation, Voc varies linearly with the temperature, T, when all the other parameters are kept constant.

This statement means that when the same electrical connection is used, the current flow will remain constant. Therefore, any change in voltage will result in a corresponding change in power, which is represented by the formula P=VI. In this experiment, the power input from the light source and the distance between the light source and the solar cell is kept constant, which means the power input is also constant. As a result, any change in voltage can be attributed solely to changes in the efficiency of the solar cell in converting light into electricity. By controlling for these other factors, the experiment can focus solely on how temperature affects the efficiency of the solar cell.

5.2 Cooling effect on the system

In this experiment, the effect of the cooling system is obtained. A comparison graph between the temperature dropped of solar panels with and without a cooling system.

Figure 8: Graph of comparison graph between the temperature dropped of solar panels with and without the cooling system

The graph shows that the solar panel with the cooling system installed reached a temperature of 45°C faster than the solar panel without the cooling system. This suggests that the cooling system is effective in reducing the temperature of the solar panel, which can potentially improve its efficiency and performance of the solar panel.

Based on the result from 5.1, the cooling system enables the efficiency value to increase from 3.8% to 4.2%, which is a 10% increase, if the temperature is successfully lowered.

6.0 Conclusion

In conclusion, the global energy demand is expected to increase in the future, and there is a need to look for sustainable energy sources. Solar power is a viable solution, but its efficiency is affected by temperature. This problem can be solved by integrating a rainwater harvesting system with the solar panel to cool it down. The collected rainwater will be used to lower the temperature of the solar panel and increase its power output. The experiment conducted showed that the solar cell's output voltage is affected by temperature. The integrated rainwater collector and solar panel cooling system will be of significant benefit to off-grid communities, enabling them to use harvested rainwater for their domestic and personal needs. Overall, this system is a sustainable way to enhance the efficiency of solar power while also addressing water scarcity issues.

7.0 References

[1] M. Gordon and M. Weber, “Global energy demand to grow 47% by 2050, with oil still top Source: US EIA,”, Oct. 06, 2021.

[2] J. Adeeb, A. Farhan and A. Al-Salaymeh, “Temperature Effect on Performance of Different Solar Cell Technologies”, Journal of Ecological Engineering, Volume 20, Issue 5, May 2019, pp. 249-254. doi:

[3] "Structure and Properties of Ceramics," American Ceramic Society, [Online]. Available: [Accessed: March 31, 2023].

[4] Katsuki, H., et al., Eco-friendly Self-cooling System of Porous Onggi Ceramic Plate by Evaporation of Absorbed Water. Journal of the Korean Ceramic Society, 2018. 55.

[5] Mosaddek, A., et al., Fabrication and experimental analysis of solar panel water cooling system. 2017.

I am a Year 2 Aerospace Engineering student at the University of Southampton Malaysia (UoSM), and also the chairperson of UoSM Institution of Engineering and Technology (IET) On Campus.